1. Field of the Invention
The present invention relates to an image recording technology for recording an image that has been captured by the use of electronic zoom.
2. Description of the Related Art
Digital cameras are designed to capture an object image with an image-sensing element and to record image data output from the image-sensing element to a recording medium.
In recording captured image data on a recording medium, some digital camera models allow selection of a recording format from the following two options:
(1) Irreversibly compressed data in, for example, JPEG format (compression format) that has gone through ordinary image processing; and
(2) Raw data that has been output from an image-sensing element (i.e., in RAW format (non-compression format)).
Of these digital cameras, some models are also capable of recording data in both JPEG and RAW formats through a single image capture operation.
There are also some models that are capable of selecting the recording size of a JPEG image or the recording size of a RAW image from multiple choices of options.
Moreover, many cameras have electronic zoom functionality to electronically enlarge an image by narrowing down an original range of data read by an image-sensing element.
If an image within such a readout range has a higher resolution than an image in the selected recording format, degradation in image quality becomes small; however, as resolutions within such a readout range become lower than those in the recording format, a zoom magnification increases and degradation in image quality thereby increases.
Japanese Patent Laid-Open No. 2001-061091 describes a technique in which the recording size of an image captured by the use of electronic zoom is kept somewhat constant. Japanese Patent Laid-Open No. 2002-077715 describes a technique in which, if the recording mode is set to a low compression rate or a non-compression format, the settings of the electronic zoom function are regulated.
In the case of enlarging an image captured by the use of electronic zoom, if the recording size of a RAW image is smaller than that of a JPEG image, a JPEG image that is generated by developing a RAW image recorded at the time of image capture suffers more severe degradation in image quality than a JPEG image recorded at the time of image capture.